A wide range of functions have been suggested for the oligosaccharides of mammalian glycoproteins. Studies designed to examine whether cells synthesize a sufficient variety of such oligosaccharides to perform these diverse functions will be carried out. The specific involvement of cell surface oligosaccharides in virus adsorption, cell differentiation and tumorigenicity will be explored. In addition, the in vivo function of organization of the biosynthetic enzymes will be examined.